Rheostat with switch



June 7, 1949. E: F, MCDONALD, JR 2,472,604

RHEOSTAT WITH SWITCH Filed Jan. 20, 1945 2 Shee'ts-Sheet 1 0 FIG. 4

' Enu enef M D M/J INVENTOR nEsw ATTOR NEY$ June 7, 1949. Mc JR2,472,604

RHEOSTAT WITH SWITCH Filed Jan. 20, 1945 2 Sheets-Sheet 2 l4 I23 H8 l2lI09 I38, :8; P 3 52 n9 I08 1 I I04 89 lv 1 9 s5 86 I33 I34 I37 FIG. 6

INVENJ'OR ATTORNEY 5 Patented June 7, 1949 UNITED STATES PATENT OFFICE 1Claim.

The present invention relates to a control system for a radio set, andmore particularly to an improved system by which certain functions of aradio receiving set, such as muting, tuning and control of the volume ofsound emitted from the loud speaker of the set, may be controlled in asimpler and more expeditious manner.

The present invention is particularly useful in connection with radioreceivers mounted in motor vehicles, although it has general applicationwherever it is desired to control a plurality of functions of a radioreceiver. The conventional hand tuning or actuation by hand of stationselectors with conventional automobile radio receiver installationconstitutes a serious hazard, as the drivers attention is distracted andserious accidents have frequently resulted. Furthermore, it is manytimes important to mute the radio receiver for short periods of time inorder to be able to listen for warning bells at railroad crossings orfor the sounds of approaching vehicles or trains. In addition, it ismany times desired to change the volume of sound emitted from the loudspeaker of the radio receiver, and in accordance with the presentinvention this function may be controlled by means in combination withthe muting and tuning means without distracting the drivers attention,

In accordance with the present invention, muting of the radio receiver,the selection of the desired signal to be received, and control of soundvolume from the receiver can be accomplished through a single memberactuated, for example, by foot control with a special type of switchmounted on the floor board of an automobile. This enables the controloperations of the radio receiver, which ordinarily require closeattention by the driver, to be carried out without requiring the driverto look at the radio set or remove either hand from the steering wheel.

Another aspect of the invention also provides a multiple circuit switchfor controlling a plurality of circuits which embodies novel features ofconstruction which permit manufacture of its parts from low cost readilyformed materials, and which also facilitate assembly of the parts.

The embodiment of the switch selected for illustrating this aspect ofthe invention is designed so it may control two electrical circuits byinterrupting both circuits in its normal position and sequentiallyclosing these circuits in a predetermined order as the switch operatoris moved from its normal to its fully operated position. The point atwhich the first circuit has been closed and the second circuit is aboutto be closed is indicated to the sense of touch of a person operatingthe switch. As the switch operator returns from its fully operatedposition to its normal position, the circuit last to be closed is openedfirst, the point where the second circuit has opened and the firstcircuit is about to be opened again being indicated to the sense oftouch. Upon completion of movement of the switch operator to the normalposition, both circuits are opened. This design also makes it possiblefor the first circuit to be closed and thereafter opened withoutdisturbing the second circuit which remains open under suchcircumstances. This design also embodies a contact spring of greatdurability and a contact arrangement which is not affected by excessiveoperating pressures. And, moreover, this design readily lends itself touse in combination with a volume control or other type of rheotateoperable by the operating member of the switch. It will be understoodthat a switch having the novel structural features to be disclosedherein may be designed to occommodate a variety of circuit controllingcontact arrangements.

The primary object of the present invention is to provide a novelcontrol system for a radio receiving set.

Another object of the present invention is to provide a novel safetycontrol system for an automobile radio receiving set.

Another object of the invention is to provide a novel device for mutinga radio receiver or selecting a desired signal, or performing both ofthese functions simultaneously.

Another object of the invention is to provide a novel device for mutinga radio receiver, selecting a desired signal, or changing the volume ofsound emitted by the loud speaker.

A still further object of the present invention is to provide a novelswitch having a plurality of operating functions which are indicated tothe sense of touch of the person operating the switch.

Another object of the invention is to provide a novel switch for closinga plurality of circuits in sequence and maintaining each circuit changeand restoring the circuits to their original condition in reverse order.

A further object of the invention is to provide a muting or tuningswitch for radio apparatus controllable by the foot of a vehicleoperator.

A still further object of the present invention is to obtainsubstantially complete shielding of the circuits of a remote tuningcontrol device connected to a radio receiver to prevent connectedto aratchet gear l8.

carriesor is otherwise connectedto a plurality of' A still furtherobject of the present. invention is to provide a novel switch'of thetype subjected to heavy operatingpressures .in which a relatively lightcontact spring of great durability is employed and in .which adjustmentof the contact arrangement is not disturbed by employment -of excessiveoperating pressures.

\ Other and morespecific objects of the inven- --tion will becomeapparent as the following de- ---taileddescription of a specificembodiment of-the -invention'proceeds with reference to the-accompanyingdrawings in'which:

Figure 1 is an elevational view partly in section of a switchembodyingtheinvention; the section being takenon line E-I ofFigure 2.

' Figure 2 is a view in plan of the switch of Figure 1.

Figure 3' is a viewin plan of a portionof the switch of Figure 1.

- Figure tie a diagrammatic"representation of a-system'in which aswitchof the invention may H be used.

Figure 5 is an' exploded view showing-the parts partially sectioned online Il"of-Figure 2.

Figure 6 is an elevational view, partlyin sec- 'tion, of modification ofthe switch of-Figure 1, "the sectionbeing taken on line 5-6-of Figure 7.

Figure 7 is a'view inplan of a portion of-the switchof Figure 6.

Figure 8 is a diagrammatic representation of a system'in'which theswitch'of Figure 6'may be used.

Figure 9 is a diagrammatic representation similar to Figure 8-=of amodified system.

The operation of the switch of -this invention,

shown in Figures 1 to 3- and 5 of-the drawings; will -be, described in"connection: withthe'rcontrol icircuits-of a muting and tuningdevice fora radio receiver. It will be understood, however, that the switch ofthis invention may be used for general :1 circuit control purposes.

Referring'to the drawings indetail and for the present to Figures 3 and4 thereof; reference numeral Ii]. indicatesptunable. radio apparatussuch as a radioreceiver having. asolenoid oper- ::;ated stationselecting. device indicated generally .by reference character I l. Thisdevice is shown diagrammatically ,as; being located exteriorly 10fthe'receiver *1 E), for the? sake of convenience of illustration. Theswitch of this invention to be described in detail hereinafter,isindicated by" reference character ll-and is operatively connected tothe device by. ashieldedmcable l l. The device comprises a shaft 17.operatively The shaft l7 switches (not shown) which connect previouslytuned sets of cooperating circuit elements in the "tunable circuits ofthe receiver so as to obtain automatic tuning-of a pluralityof presetstations. The operative connection to the tuning switches" '4 within thereceiver it is indicated by the shaft H and may be obtained by mountingthe switches on this shaft as suggested above, or in any other suitablemanner, such as by means of gears, belt drives, etc. It will beunderstood that any type of electrically operated tuning device may beoperated by the switch [2. One type of such device is shown in Patent2,216,671 granted to Eugene F. McDonald, Jr., and dated October 1, 1940.This patent mayb referred to for further details of a system of radiocontrol in which a \SWitCh of this invention may be used to obtain theadvantages pointed out herein.

The electrical connections of the tuning and muting system will now bedescribed briefly before proceeding to a detailed description of theswitch hi2. The power supply may comprise a vehicle battery 19 which isconnected to the receiver by way of a receiver power switch 2 l. Thereceiver is provided with a speaker 23 operated by a voice "coil-24supplied by the output of the receiver and 1 having one-terminalconnected to ground atZli. Conductor 2i of the cable I l-connects theother terminal of'the voice coilt i to a contact 28 -'of the switchl2.The switch 12 is preferably -mountedonthe floor boards of the vehicle inwhich the'system isinstalledor upon some part of the" vehicle easilyreached by the' occupant "thereof. The movable contact 29 oftheswitchiselectrically connected'to the grounded base plate '45 throughmembers-59, 65, till, ill and' lfl. The base plate iiiiand hence theswitch casing is "connected to ground-at "3% by way of the metallic"sheath 3! of the cable It.

The point of connecti'onto ground 36 is preferably some metallic part of'the device the circuits'of which are operated "'bythe switchlzand towhich the cable l iis connected. In Figure 4, theground. may be made i"directly'to the external casing of the receiver ii The switch l2 hasanother contact'fit connected to a solenoidtt byway of a'conductor 35.This solenoid is connectedto' one terminal of the battery Iii-throughthe receiver power 'switch"2l.

'Zifheoperatingbutton 3! serves as a switchoperatortomove' the'movablecontact 29. Depressing "the operating ,button 3? of the switch l2 causescontact 29 to engage contact'28 grounding'con- .ductor 21 to shortcircuit the voice coil ofthe speaker; through ground. This serves tomute thespeaker. Afurtherdepression of the operat- "ing button 3? of theswitch completes the circuit "throughthe-solenoid from ground at1'3tlbyway of the tcable'sheath' 3!, the contacts29, 28, and

"Ed the-conductor 36 and the batteryli].

ally'connected, asat 39, a pawl ll "The-solenoid 34 has a core 38' towhich is pivot- A pawl spring 52" biases the pawl into engagementwith1the ,teethon theiratchet wheel Hi.

'When' the circuit ',"through" the solenoid is completed, the .core" isretractedto rotate the ratchetlt in the direction indicated. After thesolenoid has rotated the ratchet to tune in a transmitting station,which occurs almost immediately, the switch button ,may: be released andthe solenoid core will be returned jto'its original position by means'ofa spring 46.

' The--switch12 the parts ofwhich are shown in section by "Figure 1 ofthe drawings, and-disassembled imFigure 5, includes a base'plate"'@'51to which is secured by tubular rivets 5i awafer-like contactassembly 36 "comprising-sheets ofxinsulating'material-"liland 48 securedtogether 'also -"by-rivets- 5 I. "The previously described-contactmemb'er fiit is secured on a protuberant portion 52 of a-metallicstrip"53- whichis retained between the sheets 41 and 48. Ear 54 on the strip53 provides a terminal to which the conductor 36 may be integrallysecured in a permanently conductive manner by soldering or welding. Thecontact 28 is secured on a resilient member such as a spiral spring 56which is secured to the insulating sheet 41 by eyelets 51. The contactspring 56 of spiral form has an inherently long life in use. Since thespring 56 is free of abrupt bends, and since its resilience does notdepend on its being bent at any one point between its ends, it is notsubject to crystallization and breakage. An upturned portion 58 providesa terminal connection for integrally receiving the conductor 21 in gOOdelectrical contact.

The cup-shaped contact enclosing member 59 is apertlned for connectionto the base plate 45 by eyelet connections 8! or other suitable means.The eyelet connections shown possess the advantage of receiving bolts,screws or other connecting means for securing the switch l2 to the floorboard or other part of the vehicle, and also, the switch may lie closelyin contact with the vehicle floor board or other part. Notches 62(Figure 2) are formed in the contact enclosing member 59 to accommodatethe insulated conductors 2'! and 36. A guide bushin $3 of insulatingmaterial is crimped to an aperture 54 located substantiallyconcentrically with respect to the contacts 28 and 33. The guide bushing63 serves a three-fold purpose in that it provides an insulatingabutment for the contact spring 56, serves as a guide for the contact 29and positions a comparatively powerful contact biasing spring 66. Thespring 65 presents two substantially flat ends, one of which rests ontop of the member 59 and the other of which reacts against a disk orwasher 8'5 which surrounds the reduced portion 88 of the circular bodyof the contact 29. The washer 57 is seated in the shoulder 69 of thecontact 29. The disk 61 preferably has an outside diameter such that itfits slidably in the cylindrical housing It which has an inwardly turnedflange H providing a restricted portion indicated by the referencecharacter '52 which serves to limit outward movement of the washer tiand thereby holds the spring 56 partly compressed. It will be seen fromthis that the movable contact 29 is guided for longitudinal movementwithout assistance from the aperture 13 in the housing IQ. At the end ofthe housing opposite the flange 7! is an outwardly turned flange it bymeans of which the housing is fastened by welding or other suitablemeans to the top of the contact enclosure member 59. Above the washer t?is a cylindrical sleeve 16. This sleeve is surrounded by another springH, which is lighter than the spring 66, and the whole is enclosed by theoperating button 3'! which is riveted onto the top of the contact 28 at18. The operating button 3! overlaps the housing Hi to prevent dirt andforeign matter from entering the switch body. In this manner the sprin'3'! is somewhat compressed under ordinary conditions. The aperture '53in the housing .53 is large enough to accommodate the spring 11. UponeX- ertion of pressure on the operating button 31 to move the contact 29toward circuit closing engagement with the contact 28, the spring TI iscompressed until the inner surface of the button 3! engages the top ofthe sleeve 15. At this time, the contact 29 is in full circuit closingengagement with the contact 28. This completes a circuit. In Figure 3,the circuit is completed from the speaker voice coil to ground in themanner explained above by grounding the conductor 21,

thereby muting the speaker. At this point, the contact has not yetengaged the contact 33. Further movement of the operating button 3'!must necessarily cause compression of the spring 66 since there is now adirect connection between the button 3?, the sleeve 13 and the washer61. The added resistance of the heavier spring 6% enables the operatorto sense the point at which the circuit of conductor 2'5 has been closedand the closing of the circuit of conductor 38 is about to occur. Uponadditional movement of the contact 29, the contact 28, which is nowgrounded by the contact 2c, engages the contact 33 to complete thecircuit to be controlled which includes conductor 36. In Figure 3, thiscircuit is completed through the solenoid 3 and serves to changestations.

In operation of the switch, it will be noted that the alignment of thecontacts 29, 28 and 33 by reason of their concentric arrangement,prevents damage or misalignment thereof by excessively heavy pressuresexerted on the operating button 3?. With the button tl' fully depressed,the thrust of contact 2.9 is talzen by the contact 28 which is solidlyin contact with the fixed contact 33. The spiral spring 56, therefore,is not called upon to resist any of the excess pressure which may beexerted on the operating button, but it is fully effective to maintainthe concentric location of the contact at. Any force tending to displacethe contact 28 laterally is prevented by the resistance to bending ofthe spring in the direction of its greatest dimension in cross section.In this respect, the spring may be regarded as a beam curved to spiralshape.

Figure 5 of the drawings serves to show the simple nature of the switchparts and the ease with which they may be assembled. While the manner ofassembling the parts of the switch [2 is believed to be apparent fromthe foregoing, a suggested mode of assembly will be briefly described.The contact spring 56 is secured to insulating sheet Al, and this andinsulating sheet 48 are assembled as a unit 46 together with the contactsuppor 53 to which contact 33 has already been secured. This unit isfastened together and secured to the base 35 by means of the rivets 5|.

The insulating guide bushing 53 may be formed into position over theaperture 64 in the contact enclosing member 59, following which theparts carried by the member 59 may be assembled to it by slipping thewasher 6! over the reduced part 833 of the contact member 29 until itrests against the shoulder 59. The contact 29 with the washer 6'! inplace is inserted upwardly through the aperture 13 in the housing 15.The sleeve l6 and the spring '5'! may then be slipped into place tosurround the reduced contact portion tB. The operating button 3'! isthen riveted in place as indicated by the reference character it. Thespring 66 may now be placed on the member 59 in a position determined bythe bushing 63. The housing It may now be secured to the contactenclosing member as by welding the flange M thereto. Assembly of theswitch is completed by crimping the fastening means 6! on the base 45 tothe contact enclosure 59 as shown in Figure 1.

Assembly of the switch l2 may be carried out in other ways to suitparticular manufacturing methods and assembling machinery if used. Theforegoing description of a suggested mode of assembly is illustrativeonly of the ease with which the switch of this invention may beassembled.

Figures 6 and '7 of the drawings disclose a modified and multiplecircuit controlling switch in accordance with the present invention. Inthis case,

"7 a combined circuit controlling switch -BI', which a'modification oftheswitch'lz of Figures 1 to 3 and 5, provides for reducing the volumeof sound as well as for muting and tuning the receiver.

Figure 8 of'the drawings discloses the modified system, and similarreference characters are used todesignate the same elements as inFigures 3 and 4. The receiver II], the station selecting device II andthe accessory equipment for the receiver are substantially like thoseillustrated in Figure 40f the drawings. The combined multiple circuitcontrolling switch BI, the parts of which are shown in section by Figure6 of the drawings, is similar in structure to the switch I2 of Figures'1 to 3 and 5 of the drawings, and is preferably I mounted on the floorboard of the vehicle in which the system is installed so as to be in aposition for convenient operation by the foot of the driver of thevehicle, or it may be installed upon some part of the vehicle easilyreached by another occupant thereof. The switch 8I is operativelyconnected to the device I I by a shielded cable 82 which encloses theconductors 83 and '84. The conductors 83 and 84 correspond to theconductors 21 and 36 of Figures 3 and 4 of 5;

the drawings. The conductor 83 of the cable '82 connects'theundergrounded terminal of the speaker voice coil 24 to the contact 85 ofthe switch I2. The conductor 84 is connected to one terminal of thesolenoid 34 and to the contact '86 of the switch 8I. The other terminalof the solenoid, which is the same as the solenoid 34 of Figure 4, isconnected to one terminal of the battery I9 through the receiver powerswitch 2!. The conductor 83 also provides a connection to the volumecontrol section 81 of the circuit controlling switch BI from the voicecoil 24 of the speaker. The operating connection between the solenoidcore 38 and the ratchet wheel I8, constituting parts of the device II,is the same as that shown in Figure 4 of the drawings.

The switch contact 85 is carried by a spiral spring member 88 and thecontact 86 is secured 'upon a contact supporting strip 89. A wafer-like"contact assembly 9|, comprising sheets of insulating material 92 and93, is secured to the base plate 94"ofth'e switch'by'tubular rivets orother suitable fastening means 96. The rivets 96 also serve to securethe sheets 92 and 93 together so as to retain the contact strip 89 inposition between sheet92 by suitable fastening means such as the eyeletsI02. An upturned portion I03 of the spring 88 provides a terminalconnection; for.

integrally receiving the conductor 83 in good electrical contact.

'The'cup-sh'aped contact enclosing member IE4 is adapted for connectionto the base plate 94 by eyelet connections I86 or other suitablesecuring means. A series of notches located in, the same position as thenotches 62 in Figure 2 of thedrawings may be provided in the annularwall of'the contact enclosing member I 04 to accomodate the insulatedconductors 83 and 84. The

re'ciprocable and rotatable contact 'III'I is guided annular member forlongitudinal movement by a guide bushing I08of insulating material whichis'crimped to'an aperture located substantially concentrically with theapertures in the contact supporting members 88 and 89. The guide bushingIDBperforr-ns substantially the same functions as the bushing =63 shownin Figures 1 and 5 of the drawings. A disk or washer'lflt surrounds thereduced portion III of the circular body of the contact I89 and isseated on theshoul-der I I2. A spring II4 presents two substantiallyflat ends, one of which rests on the member I04, and the other restsagainst the washer I09. The-washer I09 fits slidably in a cylindricalhousing IIG which has-an inwardly turned flange I I1 providing-arestricted portion indicated at H8. Outward movement of the washer Ill-9is limited by the restricted portion II8 to thereby hold the spring II4partly compressed. The housing IIB may be secured to the top of thecontact enclosure member I04 by welding its outwardly turned flange II9to the enclosure member. A cylindrical sleeve I2=I surrounds the reducedportion III of the contact Ill! and rests on the washer I89. This sleeveis surrounded by another spring I23 which is lighter than the spring II4. The aperture provided at the top of the housing H6 is large enoughto accommodate the spring I23. The combined operating knob and buttonI24, comprising the cup-shaped member I25 and'the annular member I21, isriveted onto the top of the contact member I07 as indicated by referencecharacter I28. The I21 is knurled or otherwise formed to provide aroughened surface as indicated by reference-character I 29, so that itmay be rotated by the foot of the person desiring to control thevolumeof sound emitted by theloud speaker of'the radio receiver Ill. Thecap-shaped member I25overlaps the housing II6 to prevent dirt andforeign matter from entering the switch. After the connection I28is-made the spring I23 is held incompression between the combined knoband button I24 and the washer I09. The portion of the contact II]? whichprovides the permanent connection I28 is preferably square in crosssection to fit a square aperture in'the cap member I25, thereby toinsure rotation of the contact I81 when the combined operating knob andbutton is rotated. It will be understood that any irregular shape-incross-section may be given to the portion of the contact IIZ whichprovides for the riveted connection for the purposeof insuring rotationof the contact IU'I with "the combined knob and button I24. The switchcasing is connected to ground at I36 (Figures 7 and 8) by way of themetallic sheath I3I of the cable 82. The point of connection to groundI30 is, like the point 39 of Figure 4, preferably some metallic portionof the device to which the cable 82 is connected. In Figure 8 the groundconnection may be made directly to the external casing of the receiverI8. The movable contact I81 of the switch M is electrically connected tothe grounded base plate 94 througlrthe members I84, H4, I89, I23 andI25.

The combined operating knob and button I24 is operated in the samemanner as the operating button 31 of the switch I2 of Figure 1 to muteand tune the receiver. Upon exertion of pressure on the combinedoperating knob and button I 24 to reciprocate the contact Iilltowardcircuit closing engagement with the contact 85, the top ofthesleeve I2'I is engaged by the inner'surfaoe of the combined knob andbutton following initial compression of the spring 123.

At this time the contact I'OI'is in full circuit closing engagement withthe contact 85, completing a circuit from the speaker voice coil toground by grounding the conductor 33 and thereby muting the speaker. Atthis point in its movement, the contact IU'I has not brought the contact85 into circuit closing engagement with the contact 86. Further movementof the combined knob and operating button I24 causes the spring II4 tobe compressed since there is now a direct connection between the knoband operating button I24, the sleeve I2I and the washer I09. Because ofthe added resistance of the spring II4, the operator can sense the pointat which the circuit of conductor 83 has been closed and the closing ofthe circuit of conductor 84 is about to occur. Additional movement ofthe contact I II! will cause the contact 85, which is now grounded bythe contact IN, to engage the contact 86 to complete the circuitincluding the conductor 84.

The volume control section 81 of the combined switch 8! includes avolume control rheostat I32 which may be of any well known type,adjustable by rotating its operation shaft I33. The rheostat I32 isshown as being secured to a bracket 534 by means of a nut I36. Thesupporting means for the rheostat just described is con venient sincevolume control rheostats are readily available which are of the panelmounted type shown, employing the nut I36. However, it will beunderstood that any type of rheostat may be mounted in any desiredmanner on the switch 8| with its operating shaft projecting upwardlyinto the body of the switch as shown in Figure 6 of the drawings, or thecombination of a switch and volume control may be effected in otherways. To prevent ingress of foreign matter into the volume controlsection 81 and the contacts of the switch SI, a cover member I31 isprovided which encloses the rheostat I32 and the lower end of theswitch.

The operating shaft I33 of the rheostat is slotted or bifurcated asshown at I38 so as to provide an extensible driving connection with apin at I39 projecting from side to side through a bore MI in the end ofthe contact I01. The extensible connection provided between thebifurcated end of the shaft I33 and the pin I39 permits the contact III!to be moved longitudinally in the mamier explained above to control thecircuits of the conductors 83 and 84. Rotating the combined knob andbutton I24 will adjust the amount of resistance included in the mutingcircuit, and hence will regulate the volume of sound emitted by the loudspeaker. This is preferably to be accomplished by foot operation asexplained above. The set may be muted at any time in the manner pointedout above irrespective of the angular position of the rheotat shaft I33.

The operation of the multiple circuit control system of Figure 8 willnow be explained briefly. Muting and tuning is accomplished in themanner already pointed out in connection with the de scription of thestructure of the combined switch BI. The volume of sound emitted by theloud speaker 23 is controlled by varying the amount of resistance placedin shunt with the loud speaker voice coil 24. The usual volume controlar rangement, indicated by reference character I453, ordinarily forminga part of the receiver, is operated in the normal manner to select adesired volume level, and the volume control rheostat I32 serves toreduce the volume below this level when desired. The volume controlarrangement of Figure 8 of the drawings does not interfere 10 with theuse of the ordinary volume control, nor does it interfere with theautomatic'volume control usually supplied with present day receivers.Special shielding or insulation need not be provided for the conductor83. The arrangement illustrated by Figure 8 of the drawings has theadvantage that it does not require any conductors between the combinedswitch 8! and the receiver II] in addition to those shown in Figure 4 ofthe drawings. It will be understood that the volume control section 81of the switch BI may be used to replace the regular volume control ofthe receiver if suitable precautions are taken to shield the leadsbetween the receiver and the volume control so as to substantiallyeliminate the posstray signals.

Figure 9 of the drawings is a diagrammatic showing of a modified radiocontrol system in accordance with this invention in which volume controlas well as muting and tuning may be accomplished by the combined switchSI of Figures 6 and '7 of the drawings. In this figure similar referencecharacters are used to designate the same elements as are illustrated byFigure 4. The receiver I0, the station selecting device I I and theaccessory equipment for the receiver may be of any conventional typesuch as is illustrated in Figure 4 of the drawings. Suitable outputterminals on the receiver IIi serve to energize the voice coil 24 of theloud speaker 23. The combined switch 8Ia, which is similar to the switch8| of Figures 6 and 8, is provided with a volume control potentiometerI44 which has one terminal of its resistor I46 connected to ground atany suitable point in or on the switch casing, or on the sheath I4! ofthe shielded cable I48. The remaining terminal of the resistor I46 isconnected to the muting contact 86 of the switch 8 la preferably by wayof a conductor I 49 connected to the conductor I5 I. The conductor [5|corresponds in function to the conductor 83 of Figure 8 and is connectedto one terminal of the voice coil 24 of the loud speaker, the othervoice coil terminal being grounded. The conductor I52 connects to thesolenoid 34 which performs the same function as the solenoid 34 ofFigure 4 of the drawings. A contact I54, slidable on the resistor I43,is connected to the cathode I55 of an amplifier tube I51 in the radioreceiver II) by way of a conductor I58. This tube I51 is preferably oneof the audio amplifier tubes and may be the combined detector andamplifier tube used in most present day radio receivers. The volumecontrol arrangement just described does not interfere with the use ofthe regular volume control I 59, nor does it interfere with theautomatic volume control arrangement if one is provided in the receiver.The volume control arrangement just described operates by including someof the voltage appearing across the voice coil 24 in series with thecathode circuit of an audio amplifier tube. The phase relationship ofthe voltage applied to the amplifier tube cathode is such that areduction in gain results. Since the signal voltage fed into the audioamplifier depends on the setting of the regular volume control I59 ofthe receiver, the auxiliary inverse feed back volume control of Figure 9gives a variation in audio output about a reference level established bythe main volume control. The value of the resistor I46 is not criticaland may, for standard receivers of present day design, be in theneighborhood of 500 ohms. The system of Figure 9 has the advantage ofnot requiring high impedance circuits externally of the receiver whichtendency to pickup extraneous signals or noisesgenerated by: the vehicleengine.

A- plurality of switches, such as those shown. in

Figures 1 and 6, may be'employedsothat the re-- ceiver maylee-controlled from more than one, point, The system of the presentinvention enables station changing, control of sound volume and mutingof the radio set by a. single foot-op eratcd. control device withoutthe: operator having -to look at the set, ordial, or remove his handsfrom. the automobilecontrols. The system of the v presentinventionis-particularly applicable to the control of automobile radio sets andhas been described in detail with respect to operation. from lowvoltagebatteries. However, other types of radio sets, such as sets operatedfrom alternating. current or higher voltage direct current, maybejoperated from aremote point in accordance withv the principles of thepresent invention. The invention has been illustrated in connection withan electrical type of automatic tuning wherein individual presettablecondensers or inductances are employed, but is also applicable to othertypes ofautomatic tuning arrangement.

Fromtthe foregoing detailed description of the switch of thisiinventionvit will be seen that a low cost multiple circuit switch is provided, theparts of which may be readily manufactured from cheap materials andassembled by a few relatively simple. operations.

It will also be seen that the switch of this invention may readily beadapted for controlling the volume of sound emitted by the loud speakerassociated with a radio receiver.

This application shows certain devices claimed in my co-pendingapplication Serial. No. 406,677, filed August 13, 1941 now Patent No.2,374,873 issued May 1,. 19.4.5.

While. there is shown and described here an illustrative. embodiment ofthe invention, the invention may be embodied in other forms, and

1:2 therefore thel inventionv isnot limited except as indicated by theterms and. scope of the appended claim.

. I claim:

.Incombination, ahousing, a rheostat and a pairof switches mounted insaid housing, a. common operati-ng-- member having a shaft journaledinawall-otsaid housing and an enlargedv member on the! end of said shaftoutside of said housing arrangedfor convenient rotation or linearmovem'ent of-"said-shaft; said. shaft having alongitudinal' slottherein, a pin connected with said rheostat; said pin being arranged sothat rotation-ot-said enlarged member adjusts said rheostat by rotationof said shaft and pin in any position of linear movement of said shaft,a spring having a portion fixed: in said housing and a free part spacedtherein, in the path of linear movementof said: shaft, one of saidswitches having a contact on the end. of said shaft within said hous ingand: having a second contact on the free part of said spring and theother-switch having a first contact .fixed on said free part of saidspring and a second contact fixed in said housing in the path of travelof said free'part of saidspring whereby linear movement of said shaftinto said housing first'closes'the contacts of said one switch and;later closes the contacts of said other switch and adjustment of saidrheostat by rotation of said shaft then wipes the contacts of said oneswitch.

EUGENE F; MCDONALD", JR.

REFERENCES CITED The following references are of record in the idle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,063,541 Honold June 3, 19132,015,425 Gaubert Sept. 24, 1935 2,039,117 Schellenger Apr. 28, 19362,086,752 Thornburg July 13, 1937 2,166,803 De Reamer July 18, 1939Certificate of Correction Patent No. 2,472,604. June 7, 1949.

EUGENE F. MCDONALD, JR.

It is hereby certified that errors appear in the printed specificationof the above numbered patent requiring correction as follows:

Column 2, line 19, for rheotate reed rheostat; line 23, for occommodateread accommodate; and that the said Letters Patent should be read withthese corrections therein that the same may conform to the record of thecase in the Patent Oflice.

Signed and sealed this 8th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner 0 f Patents.

Certificate of Correction Patent No. 2,472,604. June 7, 1949. EUGENE F.MCDONALD, JR.

It is hereby certified that errors appear in the printed specificationof the above numbered patent requiring correction as follows:

Column 2, line 19, for rheotate read rheostat; line 23, for occommodateread accommodate; and that the said Letters Patent should be read withthese corrections therein that the same may conform to the record of thecase in the Patent Office.

Signed and sealed this 8th day of November, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

